There are a number of earth-moving machines in the construction and mining industries today. One of the most popular earth-moving machinery is the skid steer loader because it is compact, very maneuverable and its lift arms are usable to attach many different labor saving work tool attachments. Skid steer loaders are also highly desirable because of its favorable weight ratio balance, which is achieved by locating the engine at the rear of the machine, and the load (or work tool attachment) at the front of the machine.
Generally, skid steer loaders have a frame that is moved by independently driven wheels on opposite sides of the vehicle so that by turning the left and right wheel pairs (on each side of the machine) at different speeds and in different directions, the machine turns by skidding across the ground.
In Prior Art FIG. 1, the skid steer loader 10 has a main body frame 12, which includes an operator compartment 14, that is moved by a pair of right and left wheels 16 located on opposite sides of the frame 12. A pair of lift arms 18 is pivotally mounted to the machine's frame 12 on opposite sides of the operator's compartment 14. Each lift arm 18 is equipped with a hydraulic lift cylinder 20 that raises and lowers the lift arm 18 in a vertical direction as desired.
As depicted in Prior Art FIG. 1, a work tool accessory in the form of a bucket 22 is attached to the lift arms 18. This attachment is accomplished by a work tool accessory mounting frame or coupler 24 illustrated in Prior Art FIG. 2. The work tool accessory coupler 24 is pivotally connected at 25 to a distal end of each lift arm 18. Each lift arm 18 is equipped with a hydraulic tilt cylinder 21, which is also attached to the work tool accessory coupler 24 as shown. As constructed, actuation of hydraulic tilt cylinder 21 causes the coupler 24 to tilt or retract backwards and forwards, away from and towards lift arm 18.
At its upper and lower regions, the work tool accessory coupler 24 is constructed with a lip 26 and locking pin 28, respectively, both of which fits matingly into corresponding upper and lower regions, respectively, of a work tool accessory attachment surface, that allows bucket 22 to be attached to the distal end of each lift arm 18, as shown in Prior Art FIG. 1.
Different types of work tool accessories are interchangeably attached and released from the machine 10. For this reason, a functional appeal of skid steer loaders is the ability to use a wide variety of work tool accessories or attachments for a variety of different uses. These work tool accessories or attachments are often powered by the loader's hydraulic system and include, for example, excavators, earth augers, specialized buckets, hydraulic breakers, snow blowers, trenchers, cement mixers, rippers, backhoes, pallet forks, wheel saws, etc.
In the illustration shown in Prior Art FIG. 3, the work tool accessory is in the form of a backhoe 34. As depicted, the attachment surfaces 30, 32 of the backhoe 34 is configured to fit lip 26 and pin 28 in the corresponding upper and lower regions, respectively, of the work tool accessory coupler 24 in Prior Art FIG. 2.
The upper region of the work tool accessory coupler 24 that is constructed with a lip 26 (Prior Art FIG. 2), for instance, fits matingly into a flange portion 30 (Prior Art FIG. 3) located in an upper region of the attachment surface of work tool accessory 34. Similarly, the lower region of work tool accessory coupler 24 that is constructed with a locking pin 28, is matingly fitted into aperture 32 located in a lower region of the attachment surface of work tool accessory 34. Once these mating connections are made, the work tool accessory 34 in Prior Art FIG. 3, like bucket 22 in Prior Art FIG. 1, is connected to the skid steer loader 10.
However, unlike the attachment of a compact tool like bucket 22 in Prior Art FIG. 1 to the skid steer loader 10, attachment of any work tool accessory 34 having a boom feature 36, as shown in Prior Art FIG. 3, to any skid steer loader 10 causes undesirable and unwanted machine instability even when a pair of stabilizers 38, on opposite sides of the boom feature 36 via work tool accessory 34, are employed. Machine instability is caused by a number of factors including, for example, high stress load of the boom feature 36 on the skid steer loader machine 10 such as during operation. The non-compact nature of the boom feature 36 causes another problem—undesirable forward tipping of the skid steer loader 10 in the direction of the boom feature 36, which is attached at the front or forward end of the loader machine 10. Uncontrollable or unsteady boom feature 36 support is a persistent and pervasive problem when the work tool accessory 34 manufactured by one company is attached to a skid steer loader 10 manufactured by a different company. The complex arrangement of spring locking mechanisms needed to secure the boom feature to the mounting frame is yet another typical problem.